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1

Hall Mobility Field Effect in Two Layer Conductivity Samples

100%

Mekys A., Storasta J., Zindulis A., Smilga A., Balakauskas S.

Acta Physica Polonica A

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2008

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vol. 114

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issue 4

903-912

EN

Classical Hall mobility experimental setup was applied for samples with parallel plane (sandwich) variable conductivity layers. The measured effective Hall mobility strongly depends on applied electric field and does not characterise the real carrier mobility. Numerical modelling explains the effect as a consequence of electric field redistribution and lowering at Hall contacts. Measurement of carrier mobility in such structures is suggested.

2

Optical Pump - Terahertz Probe Measurement of the Electron Dynamics in Ga_{1-x}Mn_xAs

100%

Šustavičiūtė R., Balakauskas S., Adomavičius R., Krotkus A., Sadowski J.

Acta Physica Polonica A

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2007

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vol. 112

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issue 2

311-314

EN

An optical pump - terahertz probe technique was used for measuring electron lifetime in various Ga_{1-x}Mn_xAs epitaxial layers with the subpicosecond temporal resolution. The measurements were performed on the samples with x up to 2%, which had large resistivities and were transparent in a THz frequency range. It has been found that an induced THz absorption relaxation is the fastest and electron lifetimes are the shortest for the samples with the smallest Mn content. For the samples with x=0.3% and x=2% this relaxation becomes much slower; its rate is comparable to the carrier recombination rate in Ga_{1-x}Mn_xAs substrate.

3

Low-Temperature MBE Grown GaAs for Pulsed THz Radiation Applications

86%

Adomavičius R., Balakauskas S., Bertulis K., Geižutis A., Molis G., Krotkus A.

Acta Physica Polonica A

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2005

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vol. 107

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issue 1

128-131

EN

Attempts to optimize recombination characteristics of low-temperature MBE grown GaAs layers for their use in terahertz radiation devices are described and the characteristics of this material are compared with its alternative - As-ion implanted GaAs crystals.

4

Superdiffusion in Si Crystal Lattice Irradiated by Soft X-Rays

86%

Janavičius A., Balakauskas S., Kazlauskienė V., Mekys A., Purlys R., Storasta J.

Acta Physica Polonica A

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2008

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vol. 114

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issue 4

779-790

EN

We considered the reasons of superdiffusivity and measured profiles of boron and phosphorus in crystalline silicon at room temperature. The superdiffusivity or ultrafast diffusion of metastable vacancies at room temperature in Si crystal irradiated by soft X-rays was obtained experimentally. In this work, we presented experimentally obtained diffusion coefficients of singly and doubly negatively charged long-lived excited vacancies. These high concentration charged metastable vacancies (about 10^{13} cm^{-3}) at room temperature can very fast diffuse changing electrical conductivity and the Hall mobility of carriers. We measured the superdiffusivity of negatively charged vacancies, generated by the Auger effect in the regions of the sample, which were not affected by X-rays. In this paper, we presented the obtained superdiffusion profiles of boron and phosphorus in crystalline silicon measured with secondary-ion mass spectrometer.

5

Investigation and Generation of Vacancies in Alpha Quartz by Soft X-Rays

86%

Janavičius A., Purlys R., Bulkšas A., Balakauskas S., Mekys A., Šablinskas V.

Acta Physica Polonica A

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2009

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vol. 116

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issue 6

1076-1080

EN

In this paper we applied the soft-X-ray radiation for generation of point defects, vacancies, and chemical reactions in quartz (SiO_{2}), taking into account our earlier made similar experiments with crystal silicon and importance of quartz for applications in many fields. In this case only radiative Auger's effects with electrons and electric dipole of atoms transitions can generate metastable vacancies, point defects, and induce chemical reactions. Usually, for point defects generation doses of gamma rays are used. We measured values of the Bragg reflections of X-rays and calculated mean square deviations of atoms in crystal lattice for defining the dynamics of irradiated point defects. We accomplished infrared measurements for establishing of generated chemical reactions, and conductivity measurements were also done.

6

Crystal Lattice and Carriers Hall Mobility Relaxation Processes in Si Crystal Irradiated by Soft X-rays

86%

Janavičius A., Storasta J., Purlys R., Mekys A., Balakauskas S., Norgėla Ž.

Acta Physica Polonica A

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2007

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vol. 112

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issue 1

55-68

EN

We applied soft X-rays for investigation of dynamics of the Frenkel point defects in a Si crystal during its saturation with metastable vacancies with neighboring Si atoms in excited states produced in the lattice after ejection of the Auger electrons. The irradiated irregularities and defects of the lattice cause a change of the Bragg reflection maxima. Several resonance phenomena are related to metastable states introduced into Si crystal by soft X-rays irradiation. The resonance of mean square displacements of Si atoms in the lattice and the resonance of the Hall mobility after irradiation are obtained and considered.

7

Study of Terahertz Emission from Surfaces of Cu(InGa)Se_2 Layers

73%

Koroliov A., Arlauskas A., Balakauskas S., Šoliūnas M., Maneikis A., Krotkus A., Šetkus A., Tamošiūnas V.

Acta Physica Polonica A

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2013

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vol. 124

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issue 5

846-848

EN

In this contribution, we report on investigations of THz emission from Cu(In,Ga)Se_2 layers, deposited from a single copper-deficient sputtering target. Emission from Cu(In,Ga)Se_2 layer surface and from multilayer structure with transparent ZnO layers were studied. It was determined that additional undoped ZnO layer reduces the amplitude of THz emission, while additional n-type ZnO layers increase the emission amplitude again. This effect can be attributed to stronger electric field in the heterostructure between p-type Cu(In,Ga)Se_2 and n-type ZnO layers.

8

Terahertz Detection with δ-Doped GaAs/AlAs Multiple Quantum Wells

59%

Seliuta D., Čechavičius B., Kavaliauskas J., Krivaitė G., Grigelionis I., Balakauskas S., Valušis G., Sherliker B., Halsall M., Lachab M., Khanna S., Harrison P., Linfield E.

Acta Physica Polonica A

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2008

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vol. 113

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issue 3

909-912

EN

The authors demonstrate selective detection of terahertz radiation employing berylliumδ-doped GaAs/AlAs multiple quantum wells. The sensitivity up to 1 V/W within 4.2-7.3 THz range at liquid helium temperatures is reached. The Franz-Keldysh oscillations observed in photo- and electroreflectance spectra allowed one to estimate built-in electric fields in the structures studied. It was found that the electric field strength in the cap layer region could vary from 10 kV/cm up to 26 kV/cm, depending on the structure design and temperature.

9

Broad Band THz Sensing by 2DEG Bow-Tie-Type Diodes

59%

Valušis G., Seliuta D., Tamošiūnas V., Širmulis E., Balakauskas S., Gradauskas J., Sužiedėlis A., Ašmontas S., Anbinderis T., Narkūnas A., Papsujeva I., Lisauskas A., Roskos H., Köhler K.

Acta Physica Polonica A

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2005

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vol. 107

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issue 1

184-187

EN

We suggest a novel approach to detect broad band, 0.078-2.52 THz, electromagnetic radiation at room temperature using an asymmetrically-shaped bow-tie diode based on a modulation-doped GaAs/AlGaAs structure. We show that the voltage sensitivity in the range from 0.078 THz up to 0.8 THz has a plateau and its value is within 0.3-0.5 V/W. We consider the bow-tie diode design to increase the sensitivity of the device.

Refine search results

Hall Mobility Field Effect in Two Layer Conductivity Samples

Optical Pump - Terahertz Probe Measurement of the Electron Dynamics in Ga_{1-x}Mn_xAs

Low-Temperature MBE Grown GaAs for Pulsed THz Radiation Applications

Superdiffusion in Si Crystal Lattice Irradiated by Soft X-Rays

Investigation and Generation of Vacancies in Alpha Quartz by Soft X-Rays

Crystal Lattice and Carriers Hall Mobility Relaxation Processes in Si Crystal Irradiated by Soft X-rays

Study of Terahertz Emission from Surfaces of Cu(InGa)Se_2 Layers

Terahertz Detection with δ-Doped GaAs/AlAs Multiple Quantum Wells

Broad Band THz Sensing by 2DEG Bow-Tie-Type Diodes